Hand-held scanners used for acquiring textual information from printed sources are available but all of them are bulky, most require to be connected via cable to a computer while in use and none are capable of reading along a line of text, one character at a time, to selectively read a single line of text or a portion of a single line of text.
U.S. Pat. No. 4,887,165 to Sato discloses a portable image reader, having a detachable memory, capable of scanning a document and selectively storing bit-mapped images in its detachable memory for later transfer to a computer for OCR processing and editing. The image reader of the Sato invention is designed to operate disconnected from the body of the document editing apparatus. It is moved by hand down a document such that its viewing area covers each entire line of text in succession. There is provision for selective discard of scanned images (such as portions of a page read from the document for test purposes or portions of a page that are deemed unnecessary) to improve utilization of the limited memory available. However, the device is not capable of selectively reading individual characters from a line.
U.S. Pat. No. 4,158,194 to McWaters discloses a battery-operated hand-held optical character reader, including a hand-held wand and a recognition control unit, that is capable of manual scanning of alphanumeric characters. The wand includes a keyboard and a display and is designed to be moved along a line of text such as on a label or on a document. The wand provides illumination of the label or document by use of a fiber-optic light pipe. The wand is, however, attached by a cable (or by a receive/transmit unit) to the recognition control unit which is battery operated and portable but too large to be hand-held.
U.S. Pat. No. 4,817,185 to Yamoguchi discloses an optical character reader having a hand-held scanner whose field of view covers a plurality of characters such as for reading the characters on a price tag. This scanner provides character line deletion and selects from among horizontal optical recognition ranges of various widths corresponding to possible character heights.
U.S. Pat. No. 3,947,817 to Requa discloses a hand-held optical data reader and a processor utilizing a two dimensional array of photosensitive elements capable of operation at a high frame rate. The processor is an OCR device using hardware combinational logic. The optical data reader is connected by a cable to the processor. The invention includes timing circuitry to overcome the inaccuracies arising from the loosely constrained movement of a hand-held device.
U.S. Pat. No. 3,918,028 to Humphrey discloses a hand-held optical reader having a light source and a line-array of optical sensors and the hand-held optical reader contains OCR circuitry. The OCR circuitry is capable of recognizing a limited set of characters consisting of horizontal and vertical bars.
U.S Pat. No. 4,048,617 to Neff discloses apparatus and method for detecting and discarding characters picked up on the back scan when using a hand-held optical scan unit.
U.S. Pat. No. 4,180,204 to Koenig discloses a hand-held scanner for scanning and recognizing characters on shipping labels and for marking the label on successful completion of a character recognition reading using a photosensitive dye-forming material and a UV flash.
The article "Scanners Build a Better Image", PC Magazine, Mar. 28, 1989, describes the Mitsubishi Hand-Held Image Scanner. This hand-held scanner requires cable connection to a PC and with an optional attachment is capable of reading a full 81/2 by 14 inch document. This device is not designed to scan selectively along a succession of single lines of text.
It is difficult for a user of a prior art scanner to aim the scanner and sweep the line of characters accurately because, with prior art scanners, it is impossible to view simultaneously characters before the device, directly under the device, and following the device. Accuracy of aim is critical, and the human hand is subject to variable movements that would jeopardize accurate movement.